Hydraulic fracturing (HF) generates large volumes of flowback and produced water (PW), yet the downstream relevance of injected additives remains poorly understood. Using 2020–2025 FracFocus disclosures, published chemical property information, and literature-reported PW evidence, we developed a basin-comparative screening and prioritization framework that integrates HF-event-level use relevance, fate/PW expression potential, hazard relevance, and treatment/process relevance, with evidence confidence evaluated separately and time-resolved source-term scenarios used to examine potential PW expression. Applied to 33,177 HF events in the Permian and San Juan basins, the framework identified biocides, solvents, and surfactants as the leading composite-relevance categories in the Permian, and acids, biocides, and solvents in the San Juan. Leading priorities were generally retained across sensitivity and uncertainty analyses. Mature PW salinity, major ions, metals, radionuclides, and much of the ammonia burden were predominantly formation/process controlled, whereas additive related influences were more relevant to the flowback-to-PW transition, mobile organics, toxicity related constituents, fouling, scaling, and other treatment process effects. Comparison with independent literature reported PW data provided directional external consistency for these interpretations. The framework supports basin- and production-stage-specific monitoring and treatment/reuse prioritization, but it is intended for screening rather than chemical-source attribution, predictive validation, or site-specific concentration or exposure prediction.
Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants in water and wastewater treatment, yet their behavior within engineered biofilms remains poorly resolved. This review develops a PFAS-specific, biofilm-centered framework linking PFAS molecular properties with extracellular polymeric substances, microbial surfaces, biofilm structure, and reactor conditions to explain partitioning, biological accessibility, transformation, retention, and release. A biofilm-centered mass-balance perspective is proposed to distinguish reversible retention, precursor transformation, remobilization, and verified loss from the tracked PFAS inventory. Biological transformation is emphasized as being most relevant to selected polyfluorinated precursors rather than terminal perfluoroalkyl acids. Key research needs include spatially and temporally resolved PFAS inventories and integrated measurements of biofilm and reactor states. Overall, apparent PFAS removal should not be equated with true elimination without accounting for retention, transformation, and remobilization.
Phosphate monoesters constitute an important photoreactive class of dissolved organic phosphorus (DOP) in surface waters, yet the linkage between their initial photochemical transformation and subsequent dephosphorylation remains unclear. In this study, UV photolysis experiments were conducted for adenosine monophosphate (5′-AMP), a model nucleotide phosphate monoester, to examine this linkage in a defined molecular system, together with density functional theory (DFT) calculations of its excited-state behavior, energy/electron transfer, and C-O-P cleavage pathways. 5′-AMP absorbed mainly within 200–290 nm, and short-wavelength UV markedly enhanced degradation. DOM accelerated photolysis in a concentration-dependent manner. Under irradiation with fulvic acid, the pseudo-first-order rate contribution of 3DOM* was higher than that of 1O2 and ·OH. NO3-, Cl-, and SO42- promoted degradation, whereas HCO3- and Br- inhibited it. DFT calculations using a protonated 5′-AMP reference model indicated that direct hydrolytic dephosphorylation involved a high energy barrier (~151 kJ mol−1), whereas ·OH- and 1O2-associated pre-oxidation generally lowered the barriers for subsequent water attack, with several ·OH-associated candidate routes exhibiting the lowest barriers within this model. Both natural waters exhibited higher apparent photolysis rates than ultrapure water, with a higher rate in freshwater than seawater. These differences reflected combined matrix effects involving DOM, inorganic ions, and reactive-intermediate processes, rather than any single component or reaction pathway. Overall, this work integrates experiments and theory to reveal the structure-dependence and environmental sensitivity of 5′-AMP phototransformation under the tested aqueous-matrix conditions, offering insights into light-driven abiotic dephosphorylation in aquatic P cycling and eutrophication dynamics.
Solar interfacial evaporation efficiently separates water from nonvolatile contaminants but provides limited control over pollutants retained at the evaporation interface. Here, we report a bamboo-derived adsorption-coupled solar evaporator (ASE) created by multiscale reconstruction of bamboo. The key innovation lies in a scale-differentiated bilayer design that couples active interfacial dye adsorption with phase-change separation: a polydopamine/ZIF-67-functionalized bamboo microfiber layer provides photothermal conversion and pollutant immobilization, while a directionally aligned bamboo nanofiber aerogel enables continuous water supply and thermal management. Isothermal gravimetric measurements yielded an estimated equivalent evaporation enthalpy of 1838.60 J g−1, and PDA encapsulation decreased Co release by 99.1%. Under one-sun irradiation, the ASE achieved an evaporation rate of ~3.5 kg m−2 h−1 and remained stable in 20 wt% NaCl. Removal efficiencies reached 98.75% for methylene blue and 99.50% for rhodamine B, while metal–ion concentrations in condensates decreased by >99.5%. Surface analyses supported heterogeneous multisite adsorption. This work demonstrates a renewable material platform that couples pollutant immobilization with solar-driven water purification.
We show that a physically grounded input distance fixes an ensemble persistent-homology test's geometry, and measure what that repair leaves untouched. On the ±15 d windows of three benchmark geomagnetic storms (25 event storms, 1020 calendar-matched controls), three principled longitude encodings give three reproducible verdicts: one-sided H1 resampling p=0.108 for a linear modular encoding on a single longitude convention, 0.021 for a unit sphere, 0.156 for a cylinder. Across six auditable control-draw orderings a 49-placebo calibration is nominal in H1 throughout (9–12 of 147) while H0 runs 4–16, crossing the nominal rate at its upper ordering. A great-circle distance removes the coordinate ambiguity and returns one value, and the event–control difference then survives per-window, basin, era and joint matching, though the era-matched design fails two-sided under the conservative doubling convention. It does not survive a change of the matching exponent or of the event subsample, and is absent under the true degree-2 and exact bottleneck distances. Selecting none of these, the specification-averaged p-value is 0.082 over exponents (basin-matched) and 0.122 and 0.134 over wider unmatched families, with the event above the control median in all 42 cells. We report a design- and specification-limited directional residual: no detection, and no evidence of absence.
